I would, respectfully, add a caveat to sundowner's answer.
X(し)てもらう, which means have (somebody) do X with implied benefits to
the receiver
I would replace that with
X(し)てもらう, which means have (somebody) do X with implied benefits to
the person talking (or someone in their group)
It is a very important nuance for a learner. For instance,
×あんな不良はここで待たせてもらったなんて、許されない。×
is weird, I don't see a context where it would mean something.
!あんな不良はここで待たせてもらったなんて、信じられない。!
is weird too. But one could imagine an heart-felt apology, where the no-good person is the talker's son, and the talker is very mad at his son and very impressed with the listener's indulgence. "I can't believe you would let this no-good son of mine wait here !"
{息子・僕}はそんなに豪華な所で待たせてもらって、信じられない!is natural. "I can't believe {I・my son} got to wait in such a beautiful place!"
It is also important to note that the causative+もらう form can be used more generally for polite/indirect requests/thanks.
ここで待たせてもらえますか。 "Can I please wait here?"
ここで待たせてもらえて、ありがとう。 "Thank you for letting waiting me here."